its allowed according to shia Islam.
you can ask fetwa about this from a shia scholar like below link:
Totally allow in Shia Religion to marry with Non-Shia Boy/Girl.
Sunni
Shia
Shia.
Fawad Khan is Shia
yes, it is confirmed, he is shia
there were sunni and extremely anti shia and killed shia Imams.
Shia
Shia.
He is shia.
Sahrukh khan I think he is Shia.
in both shia and sunni Islam having any sexual relation is allowed only by marriage.
according to shia its allowed a shia marry a sunni. about sunni it depends on the sect.